Clay bricks of specified low water absorption used at the base of a wall (minimum two courses) to resist the upward movement of ground water. Their use is recommended for free standing wall where otherwise a sheet of DPC material would create a plane of weakness causing the wall to be vulnerable to lateral forces.
Experiment results show that bricks with water absorption rate at 8% is 10 times more durable in resisting salt attack than that with water absorption rate at 20%. Well burnt brick has a normal water absorption rate less than 10% in contrast to that of concrete block and cement mortar exceeding 15%. This explains why brick walls require comparatively minimum maintenance in the course of time.